digestive tract (aka GI tract) -Correct Answer Covering an internal lumen (which is actually "outside" the body)
The disassembly line of our body
accessory digestive organs -Correct Answer Teeth, pancreas, assisting in mechanical and chemical digestion
Which of the following best describes ...
bio 252 exam 4 questions and answers
2024
digestive tract (aka GI tract) -Correct Answer ✔Covering an internal lumen (which is
actually "outside" the body)
The disassembly line of our body
accessory digestive organs -Correct Answer ✔Teeth, pancreas, assisting in mechanical
and chemical digestion
Which of the following best describes the role of the esophagus in digestion? -Correct
Answer ✔Connects the mouth to the stomach and has no role in chemical digestion
It's role is just propulsion
3 roles of the stomach -Correct Answer ✔1. Storage facility. Most digestion happens in
the small intestine so we just don't have enough room so we need to store in in stomach
2. Disassembly. First step in digestion of proteins. It's not essential, but it's difficult
without it.
3. Defense. Acidic environment gets rid of pathogens.
rugae -Correct Answer ✔These are the foldings inside the stomach that allow the
stomach to expand and then it makes it so it doesn't tear apart when it stretches
fundus -Correct Answer ✔store room in the stomach where some of the food waits until
we can deal with it.
3 smooth muscle layers in the stomach -Correct Answer ✔Longitudinal muscle most
external
Circular muscle within that
And then most deep, oblique muscle
The cells lining the stomach secrete mucin (mucous)
The lining is dotted with millions of gastric pits
What structural modification underlies the stomach's ability to mechanically digest food?
-Correct Answer ✔The stomach has an extra group of muscles called the oblique
muscles that are responsible for the churning and mechanical digestion of food
chyme -Correct Answer ✔Gastric juice + digestive food
either delivered in small amounts to the duodenum or forced backward into the stomach
for further mixing
The curious case of Alexis St Martin -Correct Answer ✔Dr. William Beaumont
In michigan, wanted to study the stomach and body
exam 4 bio 252
,exam 4 bio 252
Alexis St Martin was shot and it went through left part of body. Went through stomach
and out
Took different types of food and tied it to a string and put it in his stomach and waited
and took it out to see if it was digested or not.
Mucous neck cells -Correct Answer ✔in the gastric glands.
Secrete a thin mucous layer
Parietal cells -Correct Answer ✔in the gastric glands. Secrete intrinsic factor and
hydrochloric acid
Intrinsic factor has nothing to do with stomach. Really is just important protein that has
receptors on walls of small intestine that binds to essential vitamin (B12) because it
can't be digested by itself
There is a sublingual supplement (put it under your tongue)
This lets you absorb B12 directly into the capillaries in the bottom of your mouth
Chief cells -Correct Answer ✔in the gastric glands. Secrete pepsinogen. This gets
modified and becomes an active enzyme. Becomes an enzyme in an acidic
environment called pepsin. Pepsin can do digestion of proteins. Acidic environment
comes from HCL from parietal cells
HCL assists in pepsin synthesis and activity
Breaking down cell walls of plant foods
Defense against pathogens
gastric juice -Correct Answer ✔Mucus, HCL, pepsinogen
Secreted to the lumen
Enteroendocrine cells -Correct Answer ✔G cells: Gastrin
Gastrin will go back and promote secretion of gastric juice
How does gastrin from the bottom make it to parietal cells and chief cells? -Correct
Answer ✔Gastrin is a protein that serves as a hormone so it goes through the blood
vessels.
Dave Barnes had agonizing pain in his abdomen, followed by heartburn and vomiting.
The doctor told him he has a gastric ulcer in his stomach, caused by the Helicobacter
bacteria. It is most likely that the bacteria: -Correct Answer ✔Penetrated the mucus
layer of the stomach
enteric system -Correct Answer ✔Part of autonomic nervous system
From the gut
Acts as an independent system. More neurons here than in whole spinal cord
All local reflexes
The nervous system of the stomach
Long reflexes (interacts with the brain)
exam 4 bio 252
, exam 4 bio 252
Parasympathetic. Medulla oblongata controls gastric secretion and vagus nerve goes all
the way down to the stomach
Three phases of regulation -Correct Answer ✔Cephalic (head)
Gastric (stomach)
Intestinal (duodenum)
What does NOT stimulate the secretion of HCl in the stomach? -Correct Answer
✔Secretin
Secreted by the small intestine and it inhibits gastric activity
Peristaltic waves move toward the pylorus at the rate of 3 per min. How? -Correct
Answer ✔We have cells that determine the pace
regulation of gastric emptying -Correct Answer ✔In general, the same mechanisms
regulating gastric secretion will also regulate gastric emptying (mainly: intestinal phase)
Carb-rich chyme quickly moves through the duodenum (4 hours)
Fat-laden chyme is digested more slowly causing food to remain in the stomach longer
(~6 hours)
vomiting -Correct Answer ✔Stimulation of the vomiting center in the medulla
Increase in the intraabdominal pressure, relaxation of the esophageal sphincter, and
elevation of the soft palate, closing the connection between the oropharynx and
nasopharynx
from where is bile secreted? -Correct Answer ✔liver
Which system will send signals to the hepatopancreatic sphincter NOT to contract, and
when? -Correct Answer ✔When it is contracted nothing passes through
Sympathetic says no digestion when you are stressed
Intestinal phase tells it not to contract because chyme is already in it
mucosa layer lines the wall of the duodenum to do what? -Correct Answer ✔Adaptation
to digestion and absorption: fold within a fold
Stomach has 3 layers of muscle, the rest of digestive only has 2
First level of folding: circular folds
The chyme runs slowly through the duodenum, assuring complete digestion and
absorption
what structural modifications of the small intestine wall increase surface area? -Correct
Answer ✔Deep circular folds of the mucosa and submucosa
Villi: fingerlike extensions of the mucosa. have enterocytes on them
Microvilli: tiny projections of membranes of the absorptive mucosal cells on the
enterocytes. Tiny projections of plasma membranes forming a "brush border". Contain
exam 4 bio 252
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